"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

October 26, 2010

October 26 - Echinorhynchus salmonis

Echinorhynchus species are acanthocephalan parasites belonging to the family Echinorhynchidae. Like other acanthocephalans we’ve already seen (e.g. Neoechinorhynchus emyditoides; Moniliformis moniliformis; Pseudocorynosoma constrictum, these thorny headed worms parasitize the intestines of fish and amphibians. The species shown here is probably Echinorhnychus salmonis, an acanthocephalan with a Holarctic distribution, occurring in fresh and brackish waters and commonly parasitizing salmoniform and other fishes (intermediate hosts include amphipods such as Monoporeia affinis). Echinorhynchus are often the topic of research projects including effects on host feeding ecology, anti-predator behavior, and host spawning. Here are two links about Echinorhynchus species:
First Site
Second Site

Contributed by Jessica Light.


  1. why is this little guy secreting his own body?
    is he dying?

  2. I'm not sure what you mean, Daniel. The one in the photo is dead (and stained) - he's a specimen!

  3. here, see this :


    what is that fluid?

    and i have one more thing to ask.
    how do you kill a parasite which needs to become a specimen? toxin?

  4. That his "thorny head" - the proboscis that is the reason why acanthocephalans are called "thorny-headed worms. See the photo on Sept. 4th for a better look at this structure.

    Parasites are euthanized in a variety of ways, depending on what they will be used for downstream - i.e. Extracting DNA, light microscopy, electron microscopy, etc. A common way, though, is to expose them to an ever-increasing concentration of ethanol - 50%, 70%, 80%, etc., which relaxes them first and then eventually fixes them into a set shape.

  5. oh now i get it! i thought the transperant part in the other side is the thorny head.

    thank you very much susan for your time and effort for answering all my foolish questions over and over again. i really appreciate this. you are awesome.

  6. Daniel- like Susan, I appreciate your intellectual curiosity. The proboscis is the bump on the left in the photo. The bump on the right is the bursa which is used to grasp the female during copulation. You can also tell this is a male by the 2 round testes in the center of the trunk.

  7. Sorry,

    Can anyone tell me what is the different between male of Mediochrynchus sp. with this species? Because both are look alike for me.